Vibration
Thread Starter
Junior Member
Joined: Jan 2001
Posts: 12
Likes: 0
From: st. louis, mo, usa
Vibration
Hi all, just bought my first Firebird. Its 84 With T-Tops. Anyway, the engine vibrates starting at about 1700 Rpm and get worse as the RPM goes up. Any suggestions on what to check?
Senior Member
Joined: Dec 1999
Posts: 770
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From: San Antonio, TX
Car: 86Z/92 RS Camaro
Engine: 357 vortec finished. need tuning
Transmission: Still works
Axle/Gears: need 3.73
Check your harmonic balancer first to make sure it is on securely. While the car is in park, let it idle and take a look at the harmonic balancer, see if it is wobbling side to side. If it is then time to replace the HB and see if I just had a guys 85 Z28 HB fall off and one of the symptoms is a bad vibration.
Thread Starter
Junior Member
Joined: Jan 2001
Posts: 12
Likes: 0
From: st. louis, mo, usa
Did that, It looks fine. Any other suggestions?
Originally posted by 86z/92rs:
Check your harmonic balancer first to make sure it is on securely. While the car is in park, let it idle and take a look at the harmonic balancer, see if it is wobbling side to side. If it is then time to replace the HB and see if I just had a guys 85 Z28 HB fall off and one of the symptoms is a bad vibration.
Check your harmonic balancer first to make sure it is on securely. While the car is in park, let it idle and take a look at the harmonic balancer, see if it is wobbling side to side. If it is then time to replace the HB and see if I just had a guys 85 Z28 HB fall off and one of the symptoms is a bad vibration.
Junior Member
Joined: Dec 2000
Posts: 16
Likes: 0
From: Groton, CT
Car: '95Z28/'94 Trans Am/'85Z28
Engine: LT4/LT1/350
Transmission: T56/4L60/700R4
Possible out of balance driveshaft? Does it quicken with engine RPM/speed? Perhaps the SB internals are shot? Anyone else? I know the late model f-cars with the stock steel driveshaft are prone to vibration at higher highway speeds, but is this happening, let's say, in your driveway?
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Dan Young
1995 Z28/M6
Groton, CT
1984 Z28/A4 - Prospective purchase
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Dan Young
1995 Z28/M6
Groton, CT
1984 Z28/A4 - Prospective purchase
Joined: Jan 2001
Posts: 285
Likes: 14
From: the sticks of NJ...
Car: 89 Firebird Formula
Engine: 389
Transmission: T56
Axle/Gears: Moser 4.11
You didn't mention if it vibrated only
while driving, or if the vibration occurs
even if you have it in park and goose up the
rpm's.
Mine did it only when driving, and it turned
out to be the rear axle tailshaft where the
driveshaft bolts up. Seems that at one time the clambs weren't tightened sufficiently
and the yoke assembly actually wore out.
I had to replace it.
...This is on a 9 bolt borg-warner, and of course the part was discontinued a long time ago. Thank god for the GM national parts
locator service =- Only cost me $75...
------------------
89 Firebird Formula
ZZ4 Crate, WS6 package, 9 bolt rear, Hotchiss and Lakewood suspension
Edelbrock TES Headers, Random Tech 3" cat, SLP exhaust...
while driving, or if the vibration occurs
even if you have it in park and goose up the
rpm's.
Mine did it only when driving, and it turned
out to be the rear axle tailshaft where the
driveshaft bolts up. Seems that at one time the clambs weren't tightened sufficiently
and the yoke assembly actually wore out.
I had to replace it.
...This is on a 9 bolt borg-warner, and of course the part was discontinued a long time ago. Thank god for the GM national parts
locator service =- Only cost me $75...
------------------
89 Firebird Formula
ZZ4 Crate, WS6 package, 9 bolt rear, Hotchiss and Lakewood suspension
Edelbrock TES Headers, Random Tech 3" cat, SLP exhaust...
Thread Starter
Junior Member
Joined: Jan 2001
Posts: 12
Likes: 0
From: st. louis, mo, usa
It happens in park and while driving so i ruled out anything past the tranmission. I also noticed that if I go full throttle from a stop there is a loud grinding sound. Could this be related to the vibration. Like the flywheel? Being the first car, I am not the most mechanicaly inclined (yet 
)So, Im sorry if I sound like I dont know what to check for. Thanks
)So, Im sorry if I sound like I dont know what to check for. Thanks 
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